Almost every communication system includes the Quality of Service (QoS) concept in order to ensure proper communication between emitter and receiver. Even in RFID communication, the communication protocol defines CRC codes in order to check data consistency and retrials if corrupt data is received. Most RFID readers also implement RSSI reading in order to evaluate the strength of the communication link with an RFID tag.
All these QoS services are generally oriented to the communication link between the RFID reader and the RFID tag, which is the main issue in active communication systems. Battery powered systems may also include some battery level indicator in order to alert an end user when the battery has to be changed. However, this value is not related to the validity of the information it is transmitting.
Passive systems on the other hand have an additional requirement: the power transmission from RFID reader to RFID tag. If a passive RFID tag responds to the RFID reader, it is assumed that the RFID tag is powered and capable of working. However, if an external device (or load) such as a sensor or an actuator is connected to and powered from the RFID tag, the quality of the power-supply delivered to the external device is unknown. Even if this delivered power-supply is outside the required value, the RFID tag may respond to the RFID reader with uncertain or invalid information.
In such a case, the RFID reader may obtain a response from the RFID tag which may be correct from said communication link point of view, but the data included in the response may be incorrect given that the external device may have been powered with improper supply conditions.
Present invention is focused on solving such a technical problem.
There are known some patents or patent application in this technical field.
For instance, European patent EP-B1-2709041 discloses a system, and a corresponding method, for monitoring the state of health of a RFID tag. The system comprises a reader device operable to read data from said RFID tag, wherein said reader device is arranged to determine the state of health of the RFID tag by reading a parameter value indicative of said state of health from the RFID tag. In contrast to the proposed invention, the RFID tag of this patent it is not configured to power-supply an external device such as a sensor or an actuator, nor it is able to monitor said power-supply in order to know an energy state of the RFID tag.
US-A1-2008100455 provides an identification device tag including a semiconductor chip; an antenna coupled to the semiconductor chip; a layer of material, coupled to the semiconductor chip, and adapted to provide a persistent visual or audible signal that is observable by a human being; and a controller coupled to the layer of material and adapted to cause the material to provide the signal. The identification device tag may be adapted to store one or more bits indicating whether a part to which the identification device tag is coupled is included in a subset of parts in order a reader being aware of that.
US-A1-2009235106 discloses a method for determining the power supply requirements of a data processing system, wherein the data processing system is associated with a plurality of field replaceable units. The method comprises identifying, from an electronic label associated with a field replaceable unit, a unique identifier and a power supply requirement of the field replaceable unit; identifying an electronic enclosure label associated with a data processing system; associating the electronic label of a field replaceable unit with the electronic enclosure label of the data processing system; instructing the electronic enclosure label to calculate the power supply requirement of the data processing system from the identified power supply requirement of the associated field replaceable unit associated with the electronic label.
However, none of the above-mentioned patents or patent applications addresses and solves the above mentioned technical problem.